Posts Tagged ‘disease’

Ants infected with fungal pathogens steer clear of other cliques within the colony—avoiding wider infection, and allowing for a sort of immunity. Lucy Huang reports.

It’s peak cold and flu season, which means taking a lot of preventive measures. Frequent hand-washing is a must. As is avoiding co-workers or friends who are sick. But we humans are not the only animals that change behavior to keep diseases at bay. So do ants.

“So there are the foragers and the nurses– it’s two different groups of work.”

Nathalie Stroeymeyt of the University of Lausanne. She and colleagues observed ants to see their reaction to the presence of a pathogen.

“With the nurses staying inside the nurse taking care of the brood and being made of young workers. And the foragers are all the workers at outside of the nest to collect food and defend the territory.”

Forager ants are at greater risk of getting exposed to diseases because they leave the safety of the nest. So the researchers sprayed a common fungus on a small group of forager ants and then followed their movements to see the way other ants reacted.

“We marked all ants in the colony was individual labels, which carries these two-dimensional bar code marks like QR code which is automatically detected and recorded using a tracking system.”

After the infection, the nurse and forager ants stayed within their cliques and interacted less outside of their work group. The researchers also saw that forager ants spent more time outside of the nest.

“They increase that amount by 15 percent so by quite a long large amount.”

The researchers also measured the amount of fungus on each ant and saw that it was almost completely contained within the foragers group. Some nurse ants and even the Queen did have trace amounts of the fungus’ spores on them but the amount was small enough that they could easily groom them off of their bodies. The study is in the journal Science. [Nathalie Stroeymeyt et al., Social network plasticity decreases disease transmission in a eusocial insect]

Not only does the cliquish behavior stop the spread of the fungus, “but it allows you to develop immunization. Something that’s quite interesting in these ants that’s been shown by other study is that when you receive very small amount of these spores, you don’t have an increase in mortality risk because it’s low enough that you can heal, it’s sort of boost your immune defenses and protect you against later exposure to the same pathogen.

Seems that in their ability to avoid infecting other members of the community, ants may be more advanced than we are.

Biochemists, microbiologists, drug discovery experts and infectious disease doctors have teamed up in a new study that shows antibiotics are not always necessary to cure sepsis in mice. Instead of killing causative bacteria with antibiotics, researchers treated infected mice with molecules that block toxin formation in bacteria. Every treated mouse survived. The breakthrough study, published in Scientific Reports, suggests infections in humans might be cured the same way.

The molecules cling to a toxin-making protein found across Gram-positive bacterial species, called AgrA, rendering it ineffective. Treating mice with the therapeutic molecules effectively cured infections caused by methicillin-resistant Staphylococcus aureus (MRSA). S. aureus is notorious for its ability to overcome even the most potent antibiotics. Its resistance arsenal is broad, limiting therapeutic options to treat infections.

In a mouse model of S. aureus sepsis, treatment with small molecules alone resulted in 100 percent survival, while 70 percent of untreated animals died. The small molecules were as effective in promoting survival as antibiotics currently used to treat S. aureus infections. The molecules also appear to give antibiotics a boost. Septic mice treated with a combination of the small molecules and antibiotics had 10x fewer bacteria in their bloodstream than mice treated with antibiotic alone.

“For relatively healthy patients, such as athletes suffering from a MRSA infection, these molecules may be enough to clear an infection,” said Menachem Shoham, associate professor of biochemistry at Case Western Reserve University School of Medicine and senior author on the study. “For immunocompromised patients, combination therapy with the molecules and a low-dose antibiotic may be in order. The antibiotic in the combination could be one to which the bacteria are resistant in monotherapy, because our small molecules enhance the activity of conventional antibiotics, such as penicillin.”

With support from the small molecules, previously obsolete antibiotics could reenter the clinic.

Said Shoham: “This could provide a partial solution to the looming, global threat of antibiotic resistance.”

If available, antibiotics kill most bacteria, but a small number of bacteria with natural resistance survive. Over time, antibiotic-resistant bacteria multiply and spread. By Centers for Disease Control and Prevention estimates, at least two million Americans get an antibiotic-resistant infection annually. For some infections, effective antibiotics are no longer available. Disarming bacteria of disease-causing toxins represents a promising alternative to dwindling antibiotics.

Eliminating toxins frees up the immune system to eliminate bacterial pathogens instead of antibiotics, said Shoham, who also is affiliated with Q2 Pharma, Ltd., Haifa, Israel. “Without the toxins the bacteria become harmless. And since they don’t need the toxins to survive, there is less pressure to develop resistance.”

The small molecules work against multiple bacterial species. The new study included preliminary experiments showing the molecules prevent three other bacterial species from killing immune cells.

Added Shoham: “We have proven efficacy not only against MRSA but also against Staphylococcus epidermidis, which is notorious for clogging catheters, Streptococcus pyogenes that causes strep throat, Streptococcus pneumoniae, and other pathogens.”

Shoham led the study in collaboration with colleagues from the departments of biochemistry and dermatology and the Center for RNA and Therapeutics at Case Western Reserve University. The researchers developed two small molecules, F12 and F19, both of which potentiate antibiotic efficacy in the mouse models. The researchers are now working to commercialize both potential drugs. Case Western Reserve University has issued a license to Q2Pharma, Ltd., a biopharmaceutical startup company in Israel, to perform additional preclinical studies and develop F12 and F19 for clinical trials. Their initial trials will focus on patients suffering from systemic multi-drug resistant infections.

This research was supported by a Transformational Award to Menachem Shoham by the Dr. Ralph and Marian Falk Medical Research Trust Bank of America, N.A., Trustee. Some in vitro studies were supported by NIH/NIAID Preclinical Services under contract numbers HHSN272201100012I and HHSN27200007.

Dr. Leslie Norins is willing to hand over $1 million of his own money to anyone who can clarify something: Is Alzheimer’s disease, the most common form of dementia worldwide, caused by a germ?

By “germ” he means microbes like bacteria, viruses, fungi and parasites. In other words, Norins, a physician turned publisher, wants to know if Alzheimer’s is infectious.

It’s an idea that just a few years ago would’ve seemed to many an easy way to drain your research budget on bunk science. Money has poured into Alzheimer’s research for years, but until very recently not much of it went toward investigating infection in causing dementia.

But this “germ theory” of Alzheimer’s, as Norins calls it, has been fermenting in the literature for decades. Even early 20th century Czech physician Oskar Fischer — who, along with his German contemporary Dr. Alois Alzheimer, was integral in first describing the condition — noted a possible connection between the newly identified dementia and tuberculosis.

If the germ theory gets traction, even in some Alzheimer’s patients, it could trigger a seismic shift in how doctors understand and treat the disease.

For instance, would we see a day when dementia is prevented with a vaccine, or treated with antibiotics and antiviral medications? Norins thinks it’s worth looking into.

Norins received his medical degree from Duke in the early 1960s, and after a stint at the Centers for Disease Control and Prevention he fell into a lucrative career in medical publishing. He eventually settled in an admittedly aged community in Naples, Fla., where he took an interest in dementia and began reading up on the condition.

After scouring the medical literature he noticed a pattern.

“It appeared that many of the reported characteristics of Alzheimer’s disease were compatible with an infectious process,” Norins tells NPR. “I thought for sure this must have already been investigated, because millions and millions of dollars have been spent on Alzheimer’s research.”

But aside from scattered interest through the decades, this wasn’t the case.

In 2017, Norins launched Alzheimer’s Germ Quest Inc., a public benefit corporation he hopes will drive interest into the germ theory of Alzheimer’s, and through which his prize will be distributed. A white paper he penned for the site reads: “From a two-year review of the scientific literature, I believe it’s now clear that just one germ — identity not yet specified, and possibly not yet discovered — causes most AD. I’m calling it the ‘Alzheimer’s Germ.’ ”

Norins is quick to cite sources and studies supporting his claim, among them a 2010 study published in the Journal of Neurosurgery showing that neurosurgeons die from Alzheimer’s at a nearly 2 1/2 times higher rate than they do from other disorders.

Another study from that same year, published in The Journal of the American Geriatric Society, found that people whose spouses have dementia are at a 1.6 times greater risk for the condition themselves.

Contagion does come to mind. And Norins isn’t alone in his thinking.

In 2016, 32 researchers from universities around the world signed an editorial in the Journal of Alzheimer’s Disease calling for “further research on the role of infectious agents in [Alzheimer’s] causation.” Based on much of the same evidence Norins encountered, the authors concluded that clinical trials with antimicrobial drugs in Alzheimer’s are now justified.

NPR reported on an intriguing study published in Neuron in June that suggested that viral infection can influence the progression of Alzheimer’s. Led by Mount Sinai genetics professor Joel Dudley, the work was intended to compare the genomes of healthy brain tissue with that affected by dementia.

But something kept getting in the way: herpes.

Dudley’s team noticed an unexpectedly high level of viral DNA from two human herpes viruses, HHV-6 and HHV-7. The viruses are common and cause a rash called roseola in young children (not the sexually transmitted disease caused by other strains).

Some viruses have the ability to lie dormant in our neurons for decades by incorporating their genomes into our own. The classic example is chickenpox: A childhood viral infection resolves and lurks silently, returning years later as shingles, an excruciating rash. Like it or not, nearly all of us are chimeras with viral DNA speckling our genomes.

But having the herpes viruses alone doesn’t mean inevitable brain decline. After all, up to 75 percent of us may harbor HHV-6 .

But Dudley also noticed that herpes appeared to interact with human genes known to increase Alzheimer’s risk. Perhaps, he says, there is some toxic combination of genetic and infectious influence that results in the disease; a combination that sparks what some feel is the main contributor to the disease, an overactive immune system.

The hallmark pathology of Alzheimer’s is accumulation of a protein called amyloid in the brain. Many researchers have assumed these aggregates, or plaques, are simply a byproduct of some other process at the core of the disease. Other scientists posit that the protein itself contributes to the condition in some way.

The theory that amyloid is the root cause of Alzheimer’s is losing steam. But the protein may still contribute to the disease, even if it winds up being deemed infectious.

Work by Harvard neuroscientist Rudolph Tanzi suggests it might be a bit of both. Along with colleague Robert Moir, Tanzi has shown that amyloid is lethal to viruses and bacteria in the test tube, and also in mice. He now believes the protein is part of our ancient immune system that like antibodies, ramps up its activity to help fend off unwanted bugs.

So does that mean that the microbe is the cause of Alzheimer’s, and amyloid a harmless reaction to it? According to Tanzi it’s not that simple.

Tanzi believes that in many cases of Alzheimer’s, microbes are probably the initial seed that sets off a toxic tumble of molecular dominoes. Early in the disease amyloid protein builds up to fight infection, yet too much of the protein begins to impair function of neurons in the brain. The excess amyloid then causes another protein, called tau, to form tangles, which further harm brain cells.

But as Tanzi explains, the ultimate neurological insult in Alzheimer’s is the body’s reaction to this neurotoxic mess. All the excess protein revs up the immune system, causing inflammation — and it’s this inflammation that does the most damage to the Alzheimer’s-afflicted brain.

So what does this say about the future of treatment? Possibly a lot. Tanzi envisions a day when people are screened at, say, 50 years old. “If their brains are riddled with too much amyloid,” he says, “we knock it down a bit with antiviral medications. It’s just like how you are prescribed preventative drugs if your cholesterol is too high.”

Tanzi feels that microbes are just one possible seed for the complex pathology behind Alzheimer’s. Genetics may also play a role, as certain genes produce a type of amyloid more prone to clumping up. He also feels environmental factors like pollution might contribute.

Dr. James Burke, professor of medicine and psychiatry at Duke University’s Alzheimer’s Disease Research Center, isn’t willing to abandon the amyloid theory altogether, but agrees it’s time for the field to move on. “There may be many roads to developing Alzheimer’s disease and it would be shortsighted to focus just on amyloid and tau,” he says. “A million-dollar prize is attention- getting, but the reward for identifying a treatable target to delay or prevent Alzheimer’s disease is invaluable.”

Any treatment that disrupts the cascade leading to amyloid, tau and inflammation could theoretically benefit an at-risk brain. The vast majority of Alzheimer’s treatment trials have failed, including many targeting amyloid. But it could be that the patients included were too far along in their disease to reap any therapeutic benefit.

If a microbe is responsible for all or some cases of Alzheimer’s, perhaps future treatments or preventive approaches will prevent toxin protein buildup in the first place. Both Tanzi and Norins believe Alzheimer’s vaccines against viruses like herpes might one day become common practice.

In July of this year, in collaboration with Norins, the Infectious Diseases Society of America announced that they plan to offer two $50,000 grants supporting research into a microbial association with Alzheimer’s. According to Norins, this is the first acknowledgement by a leading infectious disease group that Alzheimer’s may be microbial in nature – or at least that it’s worth exploring.

“The important thing is not the amount of the money, which is a pittance compared with the $2 billion NIH spends on amyloid and tau research,” says Norins, “but rather the respectability and more mainstream status the grants confer on investigating of the infectious possibility. Remember when we thought ulcers were caused by stress?”

Cleveland Clinic researchers have discovered a new subtype of multiple sclerosis (MS), providing a better understanding of the individualized nature of the disease.

MS has long been characterized as a disease of the brain’s white matter, where immune cells destroy myelin – the fatty protective covering on nerve cells. The destruction of myelin (called demyelination) was believed to be responsible for nerve cell (neuron) death that leads to irreversible disability in patients with MS.

However, in the new findings, a research team led by Bruce Trapp, Ph.D., identified for the first time a subtype of the disease that features neuronal loss but no demyelination of the brain’s white matter. The findings, published in Lancet Neurology, could potentially lead to more personalized diagnosis and treatments.

The team’s findings support the concept that neurodegeneration and demyelination can occur independently in MS and underscore the need for more sensitive MRI imaging techniques for evaluating brain pathology in real time and monitoring treatment response in patients with the disease. This new subtype of MS, called myelocortical MS (MCMS), was indistinguishable from traditional MS on MRI. The researchers observed that in MCMS, part of the neurons become swollen and look like typical MS lesions indicative of white matter myelin loss on MRI. The disease was only diagnosed in post-mortem tissues.

“This study opens up a new arena in MS research. It is the first to provide pathological evidence that neuronal degeneration can occur without white matter myelin loss in the brains of patients with the disease,” said Trapp, chair of Cleveland Clinic’s Lerner Research Institute Department of Neurosciences. “This information highlights the need for combination therapies to stop disability progression in MS.”

In the study of brain tissue from 100 MS patients who donated their brains after death, the researchers observed that 12 brains did not have white matter demyelination. They compared microscopic tissue characteristics from the brains and spinal cords of 12 MCMS patients, 12 traditional MS patients and also individuals without neurological disease. Although both MCMS and traditional MS patients had typical MS lesions in the spinal cord and cerebral cortex, only the latter group had MS lesions in the brain white matter.

Despite having no typical MS lesions in the white matter, MCMS brains did have reduced neuronal density and cortical thickness, which are hallmarks of brain degeneration also observed in traditional MS. Contrary to previous belief, these observations show that neuronal loss can occur independently of white matter demyelination.

“The importance of this research is two-fold. The identification of this new MS subtype highlights the need to develop more sensitive strategies for properly diagnosing and understanding the pathology of MCMS,” said Daniel Ontaneda, M.D., clinical director of the brain donation program at Cleveland Clinic’s Mellen Center for Treatment and Research in MS. “We are hopeful these findings will lead to new tailored treatment strategies for patients living with different forms of MS.”

Dr. Trapp is internationally known for his work on mechanisms of neurodegeneration and repair in MS and has published more than 240 peer-reviewed articles and 40 book chapters. He also holds the Morris R. and Ruth V. Graham Endowed Chair in Biomedical Research. In 2017 he received the prestigious Outstanding Investigator award by the National Institute of Neurological Disorders and Stroke to examine the biology of MS and to seek treatments that could slow or reverse the disease.

Ionocytes (orange) extend through neighboring epithelial cells (nuclei, cyan) to the surface of the respiratory epithelial lining. This newly identified cell type expresses high levels of CFTR, a gene that is associated with cystic fibrosis when mutated.

by ABBY OLENA

Two independent research teams have used single-cell RNA sequencing to generate detailed molecular atlases of mouse and human airway cells. The findings, reported in two studies today (August 1) in Nature, reveal the gene-expression patterns of thousands of lung cells, as well as the existence of a previously unknown cell type that expresses high levels of the gene mutated in cystic fibrosis, the cystic fibrosis transmembrane conductance regulator (CFTR).

“These papers are extremely exciting,” says Amy Ryan, a lung biologist at the University of Southern California who was not involved in either study. “They’ve interrogated the cellular composition and the cellular hierarchy of the airways by using a single-cell RNA-sequencing technique. That kind of information is going to have a significant impact on advancing the research that we can do, and hopefully the derivation of new therapeutic approaches for any number of airway diseases.”

Jayaraj Rajagopal, a pulmonary physician at Massachusetts General Hospital and Harvard University and coauthor of one of the studies, had been studying lung regeneration and wanted to use single-cell sequencing to look at differences in the lungs’ stem-cell populations. He and his colleagues teamed up with Aviv Regev, a computational biologist at the Broad Institute of MIT and Harvard University, and together, the two groups characterized the transcriptomes of thousands of epithelial cells from the adult mouse trachea.

Rajagopal, Regev, and colleagues uncovered previously unknown differences in gene expression in several groups of airway cells; identified novel structures in the lung; and found new paths of cellular differentiation. They also described several new cell types, including one that the team has named the pulmonary ionocyte, after salt-regulating cells in fish and amphibian skin. These lung cells express similar genes as fish and amphibian ionocytes, the team found, including a gene coding for the transcription factor Foxi1, which regulates genes that play a role in ion transport.

The team also showed that pulmonary ionocytes highly express CFTR, and are in fact the primary source of its product, CFTR—a membrane protein that helps regulate fluid transport and the consistency of mucus—in both mouse and human lungs, suggesting that the cells might play a role in cystic fibrosis.

“So much that we found rewrites the way we think about lung biology and lung cells,” says Rajagopal. “I think the entire community of pulmonologists and lung biologists will have to take a step back and think about their problems with respect to all these new cell types.”

For the other study, Aron Jaffe, a biologist at Novartis who studies how different airway cell types are made, combined forces with Harvard systems biologist Allon Klein and his team. Klein’s group had previously developed a single-cell RNA-sequencing method that Jaffe describes as “the perfect technology to take a big picture view and really define the full repertoire of epithelial cell types in the airway.”

Jaffe, Klein, and colleagues sequenced RNA from thousands of single human bronchial epithelial and mouse tracheal epithelial cells. The atlas generated by their sequencing analysis revealed pulmonary ionocytes, as well as new gene-expression patterns in familiar cells. The team examined the expression of CFTR in human and mouse ionocytes in order to better understand the possible role for the cells in cystic fibrosis. Consistent with the findings of the other study, the researchers showed that pulmonary ionocytes make the majority of CFTR protein in the airways of humans and mice.

“Finding this new rare cell type that accounts for the majority of CFTR activity in the airway epithelium was really the biggest surprise,” Jaffe tells The Scientist. “CFTR has been studied for a long time, and it was thought that the gene was broadly expressed in many cells in the airway. It turns out that the epithelium is more complicated than previously appreciated.”

These studies are “very exciting work [and] a wonderful example of how new technologies that have come online in the last few years—in this case single-cell RNA sequencing—have made a very dramatic advance in our understanding of aspects of biology,” says Ann Harris, a geneticist at Case Western Reserve University who did not participate in either study.

In terms of future directions, the authors “have shown that transcription factor [Foxi1] is central to the transcriptional program of these ionocytes,” says Harris. One of the next questions is, “does it directly interact with the CFTR gene or is it working through other transcription factors or other proteins that regulate CFTR gene expression?”

According to Jennifer Alexander-Brett, a pulmonary physician and researcher at Washington University School of Medicine in St. Louis who was not involved in the studies, the possibility that a rare cell type could be playing a part in regulating airway physiology is “captivating.”

Apart from investigating the potential role for ionocytes in lung function, Alexander-Brett says that researchers can likely make broad use of the data from the studies—particularly details on the expression of genes coding for transcription factors and cell-surface markers. “One area that we really struggle with in airway biology . . . is [that] we just don’t have good markers” to differentiate cell types, she explains. But these papers are “very comprehensive. There’s a ton of data here.”

Tnew stroke-healing gel created by UCLA researchers helped regrow neurons and blood vessels in mice whose brains had been damaged by strokes. The finding is reported May 21 in Nature Materials.

“We tested this in laboratory mice to determine if it would repair the brain and lead to recovery in a model of stroke,” said Dr. S. Thomas Carmichael, professor of neurology at the David Geffen School of Medicine at UCLA. “The study indicated that new brain tissue can be regenerated in what was previously just an inactive brain scar after stroke.”

The results suggest that such an approach could some day be used to treat people who have had a stroke, said Tatiana Segura, a former professor of chemical and biomolecular engineering at UCLA who collaborated on the research. Segura is now a professor at Duke University.

The brain has a limited capacity for recovery after stroke. Unlike the liver, skin and some other organs, the brain does not regenerate new connections, blood vessels or tissue structures after it is damaged. Instead, dead brain tissue is absorbed, which leaves a cavity devoid of blood vessels, neurons or axons — the thin nerve fibers that project from neurons.

To see if healthy tissue surrounding the cavity could be coaxed into healing the stroke injury, Segura engineered a hydrogel that, when injected into the cavity, thickens to create a scaffolding into which blood vessels and neurons can grow. The gel is infused with medications that stimulate blood vessel growth and suppress inflammation, since inflammation results in scars and impedes functional tissue from regrowing.

After 16 weeks, the stroke cavities contained regenerated brain tissue, including new neuronal connections — a result that had not been seen before. The mice’s ability to reach for food improved, a sign of improved motor behavior, although the exact mechanism for the improvement wasn’t clear.

“The new axons could actually be working,” Segura said. “Or the new tissue could be improving the performance of the surrounding, unharmed brain tissue.”

The gel was eventually absorbed by the body, leaving behind only new tissue.

The research was designed to explore recovery in acute stroke, the period immediately following a stroke — in mice, that period lasts five days; in humans, it’s two months. Next, Carmichael and Segura plan to investigate whether brain tissue can be regenerated in mice long after the stroke injury. More than 6 million Americans are living with long-term effects of stroke, which is known as chronic stroke.

The other authors of the paper are Lina Nih and Shiva Gojgini, both of UCLA.

Activating something called the behavioral immune system puts a damper on dating, new research shows.

About a decade ago, evolutionary psychologists suggested that humans have evolved a first line of defense against disease: this behavioral immune system or BIS.

The theory is that perceiving, rightly or wrongly, the threat of disease unconsciously activates this system. Although we cannot see microorganisms with the naked eye, we are nevertheless able to identify cues—such as coughs, unpleasant smells, or skin lesions—that hint at the possible presence of pathogens, whether or not these are actually present or represent real health threats.

Scientists have suggested that the activation of the BIS leads to prejudiced and avoidant attitudes and behavior towards those who display superficial cues connoting disease.

But how does this affect our dating lives, where two competing needs are pitted against one another—i.e., the potential benefits of connecting and finding a mate versus the need to protect oneself from disease? McGill University scientists set out to find out, by looking at the activation of the BIS in young, single, heterosexual Montrealers in both real speed-dating events and in experimental online dating.

The results were convincing. And not very happy.

“We found that when the behavioral immune system was activated it seemed to put the brakes on our drive to connect with our peers socially,” says first author of the study Natsumi Sawada, who holds a PhD in psychology from McGill University.

“We hadn’t expected this to be the case in real life situations like dating where people are generally so motivated to connect. The results suggest that beyond how we consciously or unconsciously think and feel about each other there are additional factors that we may not be consciously aware of, such as a fear of disease that may influence how we connect with others.”

This video explains how the experiments worked:

The findings appear in the Personality and Social Psychology Bulletin. The Social Sciences and Humanities Research Council (SSHRC) and the Fonds de Recherche sur la Société et la Culture (FRQSC) supported the work.